Is this a converted tri fuel generator or was this natural gas from the factory?
The oil is filled at the correct level.Overfilling with oil would do that. Is there oil coming out the crankcase vent and going into the air filter box and intake?
A wider gap and/or hotter plug would reduce the tendency to foul out from burning oil.
Thank you for your help. This is the third unit I have had. The first two were changed under warranty for over and under speed issues. This unit has had multiple service calls from OJ Mann in Cheshire CT. I will tell them I have 5W30 in it. Thanks,Sam, I just read your last post to my brother. He said you should have been writing emails or letters to Briggs about this while you were still under warranty. Even now, they're PROBABLY more likely to help you as a customer than they would if an area rep contacted them for you.
He says it sounds like a valve stem seal or ring. He also said tell them you're running 5-30.
Are these engines running on NG typically harder to start than gasoline? I've noticed that when the temp is < 10 degrees the engine stumbles for 10-20 seconds before catching.